In modern auto concrete pumps, double piston pumps are generally used to feed the liquid concrete. The change between the active phases of the individual pistons gives rise to an interruption in the flow of concrete. Particularly at high feed rates this causes the jib to be excited in an impulsive fashion. This cyclic excitation gives rise to movements at the tip of the jib which constitute an nuisance during operation for the driver of the end hose. The prior art has disclosed a multiplicity of systems for actively damping elastic oscillations of the jib. Although this reduces the movements and can prevent resonance phenomena given an unfavorably adjusted pump frequency, satisfactory compensation of the movements of the jib is, rather, not possible with this.
DE 195 03 895 A1 discloses a simple position control circuit which compensates the vertical movement. However, the necessary technical measurement of the height proves problematic here. For this purpose, ultrasonic sensors and laser sensors are proposed for measuring the distance between the jib arm tip and the ground. However, this measuring principle is unfeasible in practical use since during operation it is not possible to ensure an obstacle-free space between the emitting source and the reference plane. Furthermore, it is proposed only to use the last boom joint for the implementation of the control. However, this control concept cannot be used for inclinations of the mast with respect to the gravitational field of the earth near to the vertical.
Furthermore, EP 1 537 282 B1 discloses that the height of the boom tip can be sensed relative to the height of the vehicle by means of inclination sensors which are mounted on all the boom segments. By measuring the inclinations with respect to the gravitational field of the earth it is possible to calculate the position of the boom tip with a kinematic description of the system. In this context, it is advantageous that the use of inclination sensors also causes the deformation of the boom segments to be implicitly taken into account. However, the inclination sensors which are typically used cannot differentiate between a change in the inclination and a translatory acceleration of the sensor. In the case of dynamic movements, said sensors therefore supply incorrect measurement values. Therefore they cannot be used to implement position control.